The invention relates to a storage lift having at least one charging and removal opening and a transporting unit which can be displaced vertically in a shaft between mutually opposite columns and is intended for article carriers which are to be stored, in which lift a light grille for sensing the height of the article which is to be stored is arranged at that end of the charging and removal opening which is directed toward the transporting unit, and in which lift the movement of the transporting unit during the storage and retrieval operation is automatically stopped by a safety device in the case of a foreign body which passes through the charging and removal opening penetrating into the movement path of the transporting unit.
A storage lift of the abovementioned type is known from DE 296 06 301 U1. In the known storage lift, there is arranged at the rear end of the charging and removal opening a light grille which serves alone as the sole sensor for determining the height of the article which is to be stored and, in conjunction with a corresponding control logic unit, ensures that the respective article is stored at locations where the height is as close as possible to that of the article. Light grilles which are designed for measuring the article height, unlike light barriers serving for personal protection, are usually fitted with normal, i.e. not self-testing, photocells which, on account of regulations of the trade associations for light barriers, are not authorized for personal protection. In order to protect against injuries, in particular to the hands of operators, the known storage lift is provided with two switching strips which act on safety switches and of which one is arranged above the light grille, in the charging and removal opening, and one is arranged on the bottom edge of the transporting unit. Satisfactory operation of the switching strips requires precise and durable mounting of the latter and a high level of stability in particular in the case of wide storage lifts. instead of switching strips, use is also made of light barriers which serve for personal protection, but these, unlike the light grilles for measuring the height of the article, are arranged in the front region of the charging and removal opening and, whenever operators reach into the charging and removal opening before the transporting unit is fully at a standstill, lead to so-called xe2x80x9cemergency stopsxe2x80x9d, the canceling of which naturally involves time being lost.
The object of the invention is to configure a storage lift of the generic type under consideration such that its light grille which is intended for determining the article height can additionally be utilized for personal-protection purposes. This object is achieved according to the invention in that the light grille is formed by a light grille with self-testing which can be utilized, during the movement cycles of the transporting unit, as part of the safety device and is authorized for personal-protection purposes, and in that, in order to compensate for delays brought about by the stopping operation of the transporting unit, said stopping operation being triggered by the light grille, safety aprons are arranged both on the top border of that region of the charging and removal opening which is directed toward the transporting unit and on the bottom border of the transporting unit, said bottom border being directed toward the charging and removal opening, and said aprons form barriers which partially bar the access to the shaft of the transporting unit and can execute yielding movements to extents which are sufficient in order for the transporting unit to be brought to a full standstill before the apron end position is reached.
In the storage lift according to the invention, the light grille performs a double function. With the transporting unit located in a rest position during the storage operation, it determines the height of the article, but, as soon as the transporting unit begins to mover it acts as part of the personal-protection device. Risks which could result from the position of the light grille at high speeds of the transporting unit are eliminated by the safety aprons in that the latter are dislocated or displaced, for example by an operator""s hands passing into the danger zone, to extents which are larger than the braking paths of the transporting unit. Since the outlay for the safety aprons and the mounting thereof is considerably lower than the corresponding outlay for the installation of switching strips, the solution according to the invention has proven to be not only straightforward and elegant, but also very cost-effective. The additional costs for self-testing photocells are far outweighed by the savings which can be achieved.
Further details and features of the design according to the invention can be gathered from the subclaims and from the following description of a number of advantageous embodiments illustrated in the attached drawing.